import math
x1, y1, x2, y2 = map(float, input().split())
print(math.sqrt((x1-x2)**2 + (y1-y2)**2)) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 print(math.sqrt((x1-x2)**2 + (y1-y2)**2)) print math.sqrt((x1-x2)**2 + (y1-y2)**2) math.sqrt math sqrt (x1-x2)**2 + (y1-y2)**2 (x1-x2)**2 x1-x2 x1 x2 2 (y1-y2)**2 y1-y2 y1 y2 2 x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 x2, y2 = map(float, input().split()) map(float, input().split()) x2 y2 = map(float, input().split()) map(float, input().split()) y2
import math
x1, y1, x2, y2 = map(float, input().split())
print(math.sqrt((x1-x2)**2 + (y1-y2)**2))
